Is the UNLINK command always better than DEL command?

Question

In Redis 4.0, there is a new command UNLINK to delete the keys in Redis memory.

This command is very similar to DEL: it removes the specified keys.

Answer 1

YES. please have a read on Lazy Redis is better Redis from antirez. But the reason is not that the unlink is nonblocking command. The reason is unlink is smarter than del.

UNLINK is a smart command: it calculates the deallocation cost of an object, and if it is very small it will just do what DEL is supposed to do and free the object ASAP. Otherwise the object is sent to the background queue for processing.

Also, I think the more fast way is we do the decision for redis: using DEL for small key, using UNLINK for a huge key such as big list or set. We can decrease the needless calculation of redis.